What's that noise from your boiler?

Match the noise

• Gurgling: usually air trapped in the system. Bleeding your radiators is the first step. Vaillant, Glow-worm, Ideal, Viessmann
• Gurgling when it tries to start, especially in cold weather: often a frozen or blocked condensate pipe. If it's frozen, thaw it safely. Worcester Bosch, Baxi, Ideal
• Kettling (a rumble like a kettle boiling, banging or whistling): limescale or debris on the heat exchanger. Call an engineer. Ideal, Vaillant, Viessmann, Glow-worm
• Whistling: often trapped air, so try bleeding the radiators first. If it keeps happening, it may be kettling. Ideal, Viessmann
• Banging when you turn a tap or shower off: water hammer, where the water flow suddenly reverses in the pipes. Ideal, Viessmann
• Grinding, banging or humming from the boiler: often a faulty pump. That's an engineer's job. Glow-worm, Ideal, Viessmann

What you can do yourself

1. Bleed your radiators to let out trapped air. See how to bleed a radiator. Vaillant, Ideal, Glow-worm, Viessmann
2. Check the pressure afterwards and top it up if it's dropped. Worcester Bosch, Viessmann
3. If it's freezing outside and the boiler gurgles as it tries to start, check the condensate pipe and thaw it safely. Worcester Bosch, Baxi

Call a Gas Safe engineer if

• The boiler is kettling. Vaillant says a Gas Safe engineer should inspect it, and it usually needs a chemical clean or powerflush.
• You hear grinding, humming or vibrating from the boiler itself.
• Gurgling continues after bleeding, or the condensate pipe is blocked rather than frozen.
• You smell gas at any point. Leave the property and call 0800 111 999.